Hydroplane capable of making stable turns at high speeds



NOV. 29, 1966 SWENSON 3,288,096

HYDROPLANE CAPABLE OF MAKING STABLE TURNS AT HIGH SPEEDS Filed Sept. 16, 1965 5 Sheets-Sheet 1 INVENTOR.

AR MAND D. SWEN SON BY J ATTORNEYS Nov. 29, 1966 A. D. SWENSON 3,288,096

HYDROPLANE CAPABLE OF MAKING STABLE TURNS AT HIGH SPEEDS Filed Sept. 16. 1965 5 SheetsSheet 2 INVENTOR. ARMAND D. SWENSON ATTORNEYS Nov. 29, 1966 A, D. SWENSON 3,288,096

HYDRQPLANE CAPABLE OF MAKING STABLE TURNS AT HIGH SPEEDS Filed Sept. 16, 1965 5 Sheets-Sheet 5 INVENTOR. ARMAND D. SWENSON ATTORNEYS United States Patent M 3,288,096 HYDROPLANE CAPABLE OF MAKING STABLE TURNS AT HIGH SPEEDS Armand D. Swenson, 3223 W. 154th St., Gardenia, Calif. Filed Sept. 16, 1965, Ser. No. 487,731 15 Claims. (Cl. 11466.5)

The present invention relates to hydroplanes, and more particularly to the provision of a new form of hydroplane, having inherent stability in straightaway travel and capable of making stable turns while traveling at high speed.

Conventional three-point suspension hydroplanes include two forwardly located planing surfaces or areas, disposed on opposite sides of the fore and aft centerline of the boat hull, and an after planing surface or area, disposed at the rear of the hull. They also include a forwardly disposed, upper surface portion that is relatively large in area, and transversely is of convex form. Due to a high center of gravity, and for other reasons, hydroplanes of this type bank away from rather than into their turns. This makes for a relatively unstable turn, and for safety sake requires the driver to reduce his speed while making a turn.

A principal object of the present invention is to provide a hydroplane that is centrally characterized by a central displacement hull; at least one planing ski depending downwardly from and extending along a central bottom portion of said hull; a pair of airfoil members extending laterally outwardly from upper forward locations on opposite sides of said hull, and each having a lower surface set at a definite angle of attack with respect to the direction of travel; a pair of sponsons, depending from the outboard termini of said airfoil members; and a relatively low center of gravity. Owing to this construction, hydroplanes constructed according to the present invention bank into rather than away from their turns. This, in part at least, accounts for their ability to make stable turns while traveling at high speeds.

All hydroplanes slip or slide sideways to some extent while making a turn, due to centrifugal force. In hydroplane racing terminology, this tendency of a boat to slip or slide sideways is referred to as broadsliding. When a conventional three-point suspension hydroplane broadslides, air moves relatively laterally over its convex upper surface, producing an unwanted aerodynamic lift, causing the boat to become airborne and more unstable. This phenomenon does not occur with hydroplanes constructed in accordance with the present invention. When a hydroplane constructed according to the present invention broadslides, the air it is moving against exerts a pressure on its leading side. On such side there is more surface area above than below the center of gravity. Consequently, an unbalanced force is produced above the center of gravity which acts to rotate the hull into a more pronounced bank.

Another object of the present invention is to provide a hydroplane of the character described which further includes air and water rudders, for steering purposes, both of which are located entirely below the center of gravity, so that any roll-producing effect which they have will be in the direction that puts the boat into a more pronounced bank.

A further object of the present invention is to provide a hydroplane that includes a deep V displacement hull, a central planing ski depending down from and extending along and below said hull, and a variable deadrise apparatus, especially adapted and arranged to be .used for varying the deadrise, i.e. the V characteristic, of the hull bottom.

Patented Nov. 2, 1956 bilities of hydroplanes constructed according to the present invention will be apparent from the following description of a typical form thereof, taken together with the accompanying illustrations, wherein the several figures are drawn substantially to scale, and like numerals refer to like parts, and wherein:

FIG. 1 is a side elevational view of a hydroplane constructed according to the present invention, such view showing the arrangement or disposition of the planing skis, the airfoil members, the sponsons, the propellers, the vertical and horizontal stabilizers of the tail section, and the water and air rudders, relative to the center of gravity of the hydroplane;

FIG. 2 is a top plan view of said hydroplane, showing the long chord-short span character of the airfoil members, and the sweptback nature of the leading edges of such members, and further showing the sponsons extending forwardly a substantial distance in front of the airfoil members, so as to locate a portion of the planing bottoms of such sponsons far forwardly of the center of gravity of the hydroplane;

FIG. 3 is an enlarged scale, bow end elevational view of the hydroplane of FIGS. 1 and 2, showing more clearly how the forward planing ski is related to the displacement hull, and showing the twin propeller drive, the downwardly and outwardly sloping attitude of the sponsons, and the optional variable deadrise means;

FIG. 4 is a sectional view taken through the starboard airfoil member, substantially along line 4.4 of FIG. 2;

FIG. 5 is a reduced scale nose elevational view of a conventional three-point hydroplane, showing that the center of gravity of such a hydroplane is located above a centrally disposed lift-producing surface, that it includes two planing skis, located outboardly on opposite sides of such lift'surface;

FIG. 6 is a top plan view of a hydroplane constructed according to the present invention, and of a conventional three-point hydroplane, showing them both maneuvering a left turn, such view including arrows for indicating the direction in which the hydroplanes tend to slide while turning;

FIG. 7 is an enlarged scale, nose elevational view, somewhat systematic in nature, of the hydroplane in FIG. 6 that is constructed according to the present invention, as the same is turning left, such view showing said hydroplane leaning into rather than away from the turn;

FIG. 8 is a stern end elevational view of the hydroplane shown by FIG. 7, with the vertical stabilizer, the air and water rudders, and the starboard side aileron being shown by solid lines, and the remaining parts of the hydroplane being shown schematically by broken or phantom lines, such view showing the air and water rudders located below the center of gravity of the hydroplane;

FIG. 9 is a nose end elevational view of the conventional three-point hydroplane pictured in FIG. 6, showing its tendency to lean away from rather than into the turn;

FIG. 10 is a transverse surface outline view of the forward portion of the conventional three-point hydroplane shown by FIG. 9, illustrating the chambered nature of the upper surface of such airfoil;

FIG. 11 is a comparison view of the hydroplane accord- I ing to the present invention and the conventional threepoint hydroplane, showing both of such crafts in bottom plan, and showing that in the hydroplane constructed according to the present invention, the greater portion of the lift-producing under surfaces of the airfoil members is located rearwardly of the center of gravity of the hydroplane, whereas in the conventional hydroplane the greater part of the lift-producing surface is located forwardly of the center of gravity;

FIG. 12 is a fragmentary side elevational view of the hydroplane according to the present invention, taken in the area of the two planing skis, the water rudder and the propellers, such view presenting a side elevational view of the variable deadrise means which may be used with such hydroplane;

FIG. 13 is a view like FIG. 12, but of a modified hydroplane equipped with a plurality of hydrofoils in place of the deadrise surface means;

FIG. 14 is a transverse sectional view taken substantially along line 1414 of FIG. 12, and showing by solid lines the variable deadrise hydrofoils in a shallow position, and by broken lines such hydrofoils in a deep V position;

FIG. 15 is a transverse sectional view taken through one of the hydrofoils, substantially along line 1515 of FIG. 13;

FIG. 16 is a view like FIG. 3, but of modified form of hull having fixed planing surfaces in place of the variable deadrise means; and

FIG. 17 is a view like FIG. 14, but of the hull form shown by FIG. 16.

Referring more specifically to the several figures of the drawing, FIGS. 1 and 2 show that the hydroplane of the present invention is symmetrically constructed about a longitudinally extending, vertical plane of symmetry Y. FIGS. 1-3 show such hydroplane as comprising a centrally located displacement hull 10 having a forward or bow port 12, an intermediate part or midsection 14, and an after part 16 that includes a tail section 18. Longitudinally considered, the bottom of hull is generally straight in the midsection 14; it curves upwardly as it extends forwardly through the bow part 12; and it slopes gradually upwardly as it extends rearwardly through the after part 16. The transition between the midsection 14 and the after part 16 is an abrupt one; the forward end of after part 16 is offset above the after end of midsec:

tion 14.

As perhaps best shown by FIGS. 1, 3, 12 and 13, an elongated, relatively narrow, and centrally disposed (laterally considered) planing ski 20 depends from and extends below and along the bottom of bow part 12. The planing ski 20 terminates rearwardly in a transverse step 22 that is located at approximately the same longitudinal station on the hull 10 as where the bow part 12 meets and merges into the midsection 14. This preferably occurs at about one quarter to about one third of the distance back from the nose 24 to the stern 26.

The planing ski includes a planing bottom 28 that is offset below the bottom of the bow part 12, and which also curves upwardly as it extends forwardly from the step 22. Such planing bottom may substantially merge into the bottom of bow part 12 as it approaches the nose 24. Laterally considered, the planing bottom 28 of ski 20 is relatively flat (it may be entirely fiat or set at a very slight V), whereas the displacement hull is of deep V form (see FIG. 3, for example). It may be said that the hull 10 broadens laterally as it extends upwardly from the ski 20.

A power plant 30 is housed in the bow part 12, forwardly of the step 22. A pair of counter-rotating shafts 32, 34 extend rearwardly from power plant 30, in parallel fashion, on opposite sides of the plane of symmetry, and project through the rear wall 36 of step 22. Propellers 38, 40, respectively, are provided on the after end of such shafts 32, 34,

The counter-rotating propellers eliminate the yawcausing torque that a single drive shaft and propeller would produce. The weight distribution in the hydroplane of the present invention is such that the center of gravity C.G. is located generally directly above the station of the propellers 38, 40. Water rudder 42 depends below the bottom at the after end of the midsection 14. Rudder 42 is mounted for rotation about a generally vertical axis coincident with the plane of symmetry, and such rudder 42 is located wholly below the center of gravity C.G. of the hydroplane. Water rudder 42 is preferably located at about one-half to about two-thirds of the distance back from the nose 24 to the stern 26.

A second or rear planing ski 44 may be located substantially immediately forwardly of the Water rudder 42. As illustrated, the planing ski 44 depends below the hull 10 behind and generally in line with the first ski 20. It also terminates rearwardly in a step 46, and has a planing bottom 48 that inclines forwardly from said step 46 to the bottom of the hull. The planing bottom 48 intersects the bottom of the hull at a station spaced substantially to the rear of the station of propellers 38, 40. It further includes side and rear walls that extend upwardly from the planing bottom 46 to the bottom of the hull, in similar fashion as the side and rear walls of the forward ski 20.

An air rudder 50 is shown to depend below the hull 10, preferably substantially near the longitudinal midpoint of the after part 16. It is mounted for rotation about a substantially vertical line that coincides with the aforementioned plane of symmetry Y, and preferably it is also wholly disposed below the center of gravity C.G. The air rudder 50 is preferred for high (mainly peak) speed use, but is not essential to the operation of the boat, and

may be eliminated.

The tail section 18 includes a vertical stabilizer 52, and a pair of horizontal stabilizers 54, 56 projecting laterally outwardly, on opposite sides of the vertical stabilizer 52, from vertical stations on the hull 10 spaced well above the center of gravity C.G. By way of typical and therefore non-limitive example, the upper free edge 58 of the vertical stabilizer 52 may curve upwardly as it extends rearwardly from the general vicinity of the cockpit 61 to a generally straight'top part 60. Also by way of typical example, the longitudinal side edges 64, 66 of the horizontal stabilizers 54, 56, respectively, may be substantially straight, and may diverge apart as they extend rearwardly from the general vicinity of the cockpit 61 to their outer extremities 68, 70.

A pair of airfoil members 72, 74 project laterally outwardly, on opposite sides of the hull 10, from upward forward positions on said hull 10. As clearly illustrated in FIG. 2, for example, the aspect ratio of each member 72, 74 is preferably less than one, i.e. the mean chord is larger than the span. The leading edges 76, 78 of the airfoil members 72, 74, respectively, converge together as they extend forwardly from their outer extremities to the hull 10.

As best shown by FIG. 4, considered in its entirety, the lower surface 80 of each airfoil member 72, 74 is set at a rather pronounced angle of attack relative to the direction of travel. However, the curvature of the lower surfaces 80 varies from essentially no angle of attack, or a very small angle of attack, near the leading edges '76, 78 of the members 72, 74 to a progressively larger angle of attack as the surface extends rearwardly. Preferably, a flap or aileron 82 is disposed below and hinge connected along its forward edge to the after portion of each airfoil member 72, 74. In this way the ailerons 82 are mounted for up-and-down pivotal movement about their forward edges, and their lower surfaces become an adjustable part of the lower surface 80 of the airfoil members. As more clearly shown by FIG. 3, the lower surfaces 80 are offset above and outboardly of the center of gravity C.G. In operation of the hydroplane, the surfaces 80 provide a surface effect lift, as will hereinafter be explained in greater detail.

The vertical stabilizer 52 may be provided with a trim tab 83.

The upper surfaces 84 of the airfoil members 72, 74 may be essentially flat, as illustrated, and disposed so as to take a generally horizontal attitude during travel of the hydroplane. Alternatively, the upper surfaces 84 may be cambered to provide a greater lift.

An elongated, relatively narrow sponson depends below the outer extremity of each airfoil member 72, 74. The

sponsons, designated 86, 88, respectively, have forwardly and upwardly curving bottoms, that are offset a substantial distance above the planing bottom of the planing skis 20, 42, and a substantial distance below the lower surfaces 80 of said airfoil members 72, 74. The sponsons 86, 88 slope outwardly from top to bottom a sufficient amount so that in a turn the inside sponson is disposed substantially upright when its lower portion is in the water (FIG. 7). The inboard side surfaces 90, 92 of the sponsons 86, 88 preferably slope outwardly from top to bottom a greater amount so that in the turn the inside side surface of the inside sponson still slopes outwardly and downwardly from top to bottom, as indicated by the angle x in FIG. 6. This arrangement allows the hydroplane to broadside without jamming (i.e. daming up) water at A (FIG. 7).

Referring again to FIG. 1, the trim or at least water line TL is indicated generally by the line TL, and the water line when the hydroplane is planing is designated generally at W11. During the at rest conditions, and while the hydroplane is traveling at relatively slow speeds, the lower portion of the displacement hull 10, and the lower portions of the sponsons 86, 88 are under water. As the speed of travel is increased, the hydroplane rises in the water. It first rides with the lower portion of the hull 10 in the water, then it planes on he bottom of hull 10, and then it rises until the only contact with the water is made by the after portion(s) of the planing bottom(s) of the planing ski(s). By way of typical example, the hydroplane may plane on the main hull at about eighteen miles per hour, and on the ski( s) at about forty miles per hour, and full planing may occur at about sixty miles per hour. As will be evident, the sponsons 86, 88 will have cleared the surface of the water prior to planing on the ski(s).

As the hydroplane moves forwardly, the air contacted by the lower surfaces 80 of the airfoil members 72, 74 is deflected downwardly thereby toward the water. This produces an initial reaction lift due to the change in the direction of relative flow. This lift is augmented due to the fact that the air so turned is for a time trapped between the lower surfaces 80 of the airfoil members 72, 74 and the upper surface of the water. This provides a cushion of 'air on which the hydroplane rides While traveling at high speeds.

As will be evident, the lift can be further enhanced by lowering the flaps or ailerons, so as to stee-pen the angle of attack of the after portion of the lift-producing surfaces 80. The ailerons are, of course, independently operable and at times are employed separately, such as when the hydroplane is being turned, for example. Referring now to FIGS. 3 and 5, FIG. 3 is a nose end elevational view of a preferred embodiment of the invention, and FIG. is a nose elevational view of a conventional three-point suspension hydroplane. In comparison, the center of gravity of C.G. of the hydroplane constructed according to the present invention is relatively low in comparison with the height of the entire boat, and the lift-producing surfaces are spaced laterally outwardly from, and a substantial distance above the center of gravity C.G. In the conventional three-point hydroplane the center of gravity C.G. is high, relatively speaking, and it is located above the greater portion of the lift-producing surface LS, and such surface LS is centrally disposed. The planing skis S are spaced outboardly of such surface LS. As indicated by the directional arrows, this type of hull tends to fall off from side to side while planing, pivoting about the center of gravity C.G. In contrast, in the hydroplane constructed according to the present invention, the air support or lift is provided on each side and above the center of gravity C.G. resulting in good lateral stability, and the surfaces 80 are dihedrally related, for additional stability.

FIG. 11 is a side-by-side bottom plan view comparison of the two types of hydroplanes. This view shows that the area center of the lift-producing surfaces 80 is located rearwardly of the center of gravity C.G. in the hydroplane constructed according to the present invention, and that in the conventional three-point suspension hydroplane, the area center AC is located forwardly of the center of gravity C.G. In the hydroplane constructed according to the present invention more air lift is provided rearwardly than forwardly of the center of gravity C.G. whereby an unbalanced force is created which tends to rotate the tail section upwardly and maintain the hydroplane in the attitude shown by FIG. 1. In the conventional three-point suspension hydroplane, more of the lift-producing surface is located forwardly than rearwardly of the center of gravity C.G., resulting in the nose of the boat being lifted upwardly.

FIG. 9 is a view like FIG. 5, but showing the conventional three-point suspension hydroplane in the attitude which it takes while in a left turn. Owing to its relatively high center of gravity C.G., such hydroplane banks away from rather than into the turn. While turning some broadsiding occurs, and the direction of sideways movement is indicated by arrows in FIGS. 6 and 9.

As indicated by directional arrows in FIG. 10, as the conventional hydroplane slides sideways air flows relatively laterally over its convex upper surface. This reduces the pressure above the boat, and if such boat is traveling at too fast a speed, the higher pressure in the tunnel area causes the boat to become airborne. When this happens the boat is unstable and there is danger of its tipping over. Therefore, to prevent tipping it is necessary for the driver to reduce his speed before making a turn.

While turning, a hydroplane constructed according to the present invention banks into rather than away from the turn (FIGS. 7 and 8), and broadsiding causes a more pronounced bank. This is because on the sides of the boat there is more surface area located above than below the center of gravity CG. When the boat moves sideways (i.e. broadsides) the air which it is moving against exerts a pressure on the leading side. Owing to the area differential, the forces produced by such air pressure are unbalanced with respect to the center of gravity, and tend to rotate the boat into a more pronounced bank. As a result, the boat is capable of making a stable turn at high speeds, and it is unnecessary to reduce the speed an appreciable amount while making a turn.

The water rudder 42 (and also the air rudder 50 in boats that are also equipped with air rudder 50) is used for turning the boat. Since it is located below the center of gravity CG, it also helps to bank the boat in the proper direction. While turning, air moves relatively across the inside surface of the vertical stabilizer 52. Such vertical stabilizer 52 is trimmed in the same direction as the water rudder 42, and has a rotational effect on the boat tending to bank it the wrong way, i.e. away from the turn. Since the water and air rudders 42, 50, respectively, are located below the center of gravity, their rotational effect will act to counter the rotational effect of the vertical stabilizer 52. If necessary, the outside flap or aileron 82 may be moved down so as to increase the lift on its side of the boat and cause the boat to bank into the turn an additional amount (FIG. 8). i

The sponsons 86, 88 function to keep the boat from barrel rolling at high speed when the rudder is turned. The water rudder acts as a rudder and an aileron simultaneously, and in extreme turns, it becomes an elevator and lifts the tail, giving the hull 10 a nose-down attitude. The sponsons are elongated forwardly from the leading surface of the airfoil members from which they depend, so that in the case of an engine failure, causing the propellers to lock, with ensuing uneven drag to one of the boat sides, making the boat dip forwardly on either its port or starboard quarter, there will be sufiicient amount of support surface forwardly of the center of gravity C.G. in the direction of dipping to prevent the boat from turning over.

The displacement hull 10 may be provided with a variable deadrise apparatus, comprising a pair of deadrise means 94, 6 (FIGS. 3, 12 and 14), or several sets of hydrofoils 94', 96' (FIGS. 13 and 15), hinge connected to the bottom of the hull in the general vicinity of where such bottom is intersected by the generally vertical sides of the planing ski 20 (FIGS. 1214). The deep V displacement hull 10 provides for cruising comfort. Less pounding is experienced with a hull of this shape. Generally speaking, the deeper the V, the softer the ride in rough water. However, a relatively flat bottom is preferred for planing. A hull bottom with a low degree of deadrise makes a better planing surface than a bottom with a high degree of deadrise. Thus, for lifting efficiency, a low degree of deadrise is preferred.

The variable deadrise apparatus of the present invention makes it possible to have a deep V hull available for taking rough water, and a relatively shallow V bottom available for planing. As shown by FIG. 14, the variable angle hydrofoils 94, 96 may be adjusted in position by means of actuator rods 98 attached to such hydrofoils 94, 96 adjacent their outboard edges, and extending therefrom through openings therefor in the bottom of the hull 10, to hydraulic or electrical actuators (not shown), or the like. Alternatievly, pneumatic cushions may be used in place of such actuators. Examples of such cushions are disclosed by Stampel US. Patent No. 2,265,206 and Parker 2,347,881 in different settings.

FIGS. 16 and 17 disclose a hull having a relatively flat, somewhat crescent shaped, fixed planing surface on each side. This type of hull will plane at lower speeds than the deep V hull.

From the foregoing consideration of various aspects of the invention, other arrangements, adaptations and modifications of the invention will occur to those skilled in the art to which the invention is addressed, and are to be considered to be within the scope of the invention as defined by the following claims:

What is claimed is:

1. A hydroplane, symmetrically constructed about a longitudinally extending, vertical plane of symmetry, and comprising:

(a) an elongated, relatively narrow, planing ski having a planing bottom;

(b) a displacement hull extending above and broadening out laterally from said ski;

(c) a pair of airfoil members projecting laterally outwardly on opposite sides of the hull, from an upper forward portion of said hull, and each having a lower, surface-effect surface set at a pronounced angle of attack with respect to the direction of travel,

with the center of gravity of said hydroplane being located substatnially below the said lower, surface-effect surfaces of the airfoil members, and above the planing bottom of said planing ski, substantailly in the vertical plane of symmetry, and said hydroplane further comprising:

(d) a tail section including a vertical stabilizer extending above the hull and entirely above the center of gravity of the hydroplane;

(e) a water rudder depending below said hull, intermediate the length of said hydroplane, including means mounting it for pivotal movement about a generally vertical axis; and

(f) an air rudder depending below said hull, rearwardly of the Water rudder, and including means mounting it for pivotal movement about a generally vertical ax1s,

with said water and air rudders both being disposed substantially entirely below the center of gravity of the hydroplane.

2. A hydroplane according to claim 1, further comprising an elongated, relatively narrow, sponson depending from and below the outer extremity of each airfoil member.

3. A hydroplane according to claim 1, further com-prising an aileron disposed below and hinge connected along its forward edge to the after portion of each airfoil member, for up and down pivotal movement about said forward edge, and having a lower surface forming a rearward continuation of the lower surface of said airfoil member.

4. A hydroplane, symmetrically constructed about a longitudinally extending, vertical plane of symmetry, and comprising:

(a) an elongated, centrally disposed, and relatively broad displacement hull having a single prow bow and a bottom, said bottom curving forwardly and upwardly in the region of said bow, fro-m a station spaced substantially forwardly of the longitudinal center of said hull;

(b) a relatively narrow, centrally disposed, planing ski depending below and formed integral with said bow, and terminating rearwardly in a transverse step, generally at the station where the bottom of said bow commences to curve forwardly and upwardly, said planing ski having a planing bottom that is offset below the bottom of said bow, a pair of laterally spaced apart sides extending upwardly from said planing bottom to the bottom of said bow, and a rear wall at said step, also extending upwardly from said planing bottom to the bottom of said bow;

(c) a pair of airfoil members projecting laterally outwardly from upper forward portions of said hull, one on each side of the hull, such members having lower surfaces set at a pronounced angle of attack during normal use, for producing a surface-effect lift outboar-dly of said hull, on each side thereof;

(d) a pair of elongated, relatively narrow, sponsons, one depending from and below the outer extremity of each airfoil, said sponsons having forwardly and upwardly curving bottoms, offset a substantial distance above the planing bottom of said planing ski, and offset a substantial distance below the lower surfaces of said airfoil members;

(e) a tail section integral with the after portion of said hull, and including a vertical stabilizer projectting upwardly from the after portion of said hull, and a pair of horizontal stabilizers projecting laterally outwardly from the base of said vertical stabilizer on opposite sides of the hull; and

(f) a power plant in said hull, forwardly of said step,

and including at least one drive shaft extending rearwardly through the bottom of said displacement hull, generally at said step, and -a propeller on the after end of said shaft,

with the center of gravity of said hydroplane being located generally directly above said propeller and a substantial distance below the lower surfaces of the airfoil members.

5. A hydroplane according to claim 4, wherein the airfoil members have forwardly converging leading edges, and the sponsons project substantially forwardly of the outer extremities of such leading edges.

6. A hydroplane according to claim 4, wherein the airfoil members have forwardly converging leading edges, and the chord dimension of each member, at its outer extremity, is larger than the span dimension.

7. A hydroplane according to claim 4, wherein the areas centers of the lower surfaces of the airfoil members are located rearwardly of the center of gravity of the hydroplane.

8. A hydroplane according to claim 4, wherein the sponsons slope outwardly from top to bottom a sufiicient amount so that in a turn the inside sponson is disposed substantially upright when its lower portion is in the water.

9. A hydroplane according to claim 4, further including an aileron disposed below and hinge connected along its forward edge to the after portion of each airfoil member, for up and down pivotal movement about said forward edge, and having a lower surface forming a rearward continuation of the lower surface of said airfoil member.

10. A hydroplane according to claim 4, wherein the said power plant includes a pair of counter-rotating drive shafts extending rearwardly from said hull, one on each side of the vertical plane of symmetry, with a propeller on the after end of each such shaft.

11. A hydroplane according to claim 4, wherein the bottom of said hull slopes upwardly as it extends rearwardly from a station to the rear of the longitudinal center of such hull, and an air rudder is pivotally mounted on and depends below the after portion of said hull, and is located below the center of gravity of the hydroplane, and above the water surface when the hydroplane is plan- 12. A hydroplane according to claim 4, wherein the displacement hull is of V shape in transverse cross-section, in at least the portion thereof above the planing ski, and said hydroplane further includes variable deadrise means comprising at least one pair of relatively thin hydrofoil members, means pivotally connecting the inboard edges of said members onto the displacement hull, generally where its bottom and the side walls of the planing ski intersect, and means for moving such members between shallow and deep deadrise positions.

13. A hydroplane according to claim 4, wherein a water rudder is pivotally mounted on and depends below 10 said hull, to the rear of said propeller, and is located below the center of gravity of the hydroplane.

14. A hydroplane according to claim 13, wherein a second centrally disposed planing ski depends below said hull, behind and generally in line with the first ski, and substantially immediately forwardly of said water rudder, said second ski terminating rearwardly in a step and having a planing bottom that inclines forwardly from said step to the bottom of the hull, and intersects the bottom of the hull at a station spaced substantially to the rear from said propeller, and side and rear walls that extend upwardly from the planing bottom to the bottom of the hull.

15. A hydroplane according to claim 14, wherein the bottom of the hull inclines rearwardly from the locality of the water rudder, and an air rudder is pivotally mounted on and extends below said hull, between the water rudder and the stern, below the center of gravity of the hydroplane, above the water rudder, and above the water surface during planing.

No references cited.

MILTON BUC-HLER, Primary Examiner.

ANDREW H. FARRELL, Examiner. 

1. A HYDROPLANE, SYMMETRICALLY CONSTRUCTED ABOUT A LONGITUDINALLY EXTENDING, VERTICAL PLANE OF SYMMETRY, AND COMPRISING: (A) AN ELONGATED, RELATIVELY NARROW, PLANING SKI HAVING A PLANING BOTTOM; (B) A DISPLACEMENT HULL EXTENDING ABOVE AND BROADENING OUT LATERALLY FROM SAID SKI; (C) A PAIR OF AIRFOIL, MEMBERS PROJECTING LATERALLY OUTWARDLY ON OPPOSITE SIDES OF THE HULL, FROM AN UPPER FORWARD PORTION OF SAID HULL, AND EACH HAVING A LOWER, SURFACE-EFFECT SURFACE SET AT A PRONOUNCED ANGLE OF ATTACK WITH RESPECT TO THE DIRECTION OF TRAVEL, WITH THE CENTER OF GRAVITY OF SAID HYDROPLANE BEING LOCATED SUBSTANTIALLY BELOW THE SAID LOWER, SURFACE-EFFEC SURFACE OF THE AIRFOIL MEMBERS, AND ABOVE THE PLANING BOTTOM OF SAID PLANING SKI, SUBSTANTIALLY IN THE VERTICAL PLANE OF SYMMETRY, AND SAID HYDROPLANE FURTHER COMPRISING: (D) A TAIL SECTION INCLUDING A VERTICAL STABILIZER EXTENDING ABOVE THE HULL AND ENTIRELY ABOVE THE CENTER OF GRAVITY OF THE HYDROPLANE; (E) A WATER RUDDER DEPENDING BELOW SAID HULL, INTERMEDIATE THE LENGTH OF SAID HYDROPLANE, INCLUDING MEANS MOUNTING IT FOR PIVOTAL MOVEMENT ABOUT A GENERALLY VERTICAL AXIS; AND (F) AN AIR RUDDER DEPENDING BELOW SAID HULL, REARWARDLY OF THE WATER RUDDER, AND INCLUDING MEANS MOUNTING IT FOR PIVOTAL MOVEMENT ABOUT A GENERALLY VERTICAL AXIS, WITH SAID WATER AND AIR RUDDERS BOTH BEING DISPOSED SUBSTANTIALLY ENTIRELY BELOW THE CENTER OF GRAVITY OF THE HYDROPLANE. 